Expression of all six human Torque teno virus (TTV) proteins in bacteria and in insect cells, and analysis of their IgG responses.
Torque teno virus (TTV) is a non-enveloped human virus with a circular ( approximately 3800 nt) ssDNA genome. TTV transcription results in three viral mRNAs and six proteins, the function or antigenicity of which are unknown. The six open reading frames of TTV genotype 6 were expressed in bacteria and insect cells. Expression of the ORF1/1-encoded protein was inefficient, while expression of the others was successful, with ORF1 and ORF1/2 as arginine-rich region depleted. All six recombinant TTV proteins were antigenic. Of healthy adults, 11/25 (44%) showed strong IgG reactivity with one or more proteins. Four subjects, two of whom were genotype-6-DNA positive, were followed. One of the latter showed concurrently a strong IgG response against the ORF1 protein. The other showed appearance of IgG against the ORF2 protein concomitantly with resolution of the genotype-6 viremia. The genotype-6 sequences remained unaltered for years, suggesting that some mechanisms other than amino acid substitutions play a role in TTV immune evasion.
Kakkola
Laura
L
Department of Virology, Haartman Institute and Helsinki University Central Hospital Laboratory, Haartmaninkatu 3, P.O. Box 21, University of Helsinki, FIN-00014, Finland. laura.kakkola@helsinki.fi
Bondén
Heidi
H
Hedman
Lea
L
Kivi
Niina
N
Moisala
Susanna
S
Julin
Jaakko
J
Ylä-Liedenpohja
Jussi
J
Miettinen
Simo
S
Kantola
Kalle
K
Hedman
Klaus
K
Söderlund-Venermo
Maria
M
D000328:Adult; D000818:Animals; D000914:Antibodies, Viral / Q000096:biosynthesis; D000956:Antigens, Viral / Q000096:biosynthesis / Q000235:genetics; D001483:Base Sequence; D002460:Cell Line; D004266:DNA Virus Infections / Q000276:immunology / Q000821:virology; D004279:DNA, Viral / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics; D015870:Gene Expression; D005814:Genes, Viral; D006801:Humans; D007074:Immunoglobulin G / Q000096:biosynthesis; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000235:genetics / Q000276:immunology; D018411:Spodoptera; D022783:Torque teno virus / Q000235:genetics* / Q000276:immunology*; D014764:Viral Proteins / Q000096:biosynthesis / Q000235:genetics* / Q000276:immunology*
D000914:Antibodies, Viral; D000956:Antigens, Viral; D004279:DNA, Viral; D007074:Immunoglobulin G; C446939:ORF1 protein, TT virus; C524331:ORF2 protein, Torque teno virus; D011994:Recombinant Proteins; D014764:Viral Proteins